"As currently proposed, Secure Boot impedes free software adoption. It is already bad enough that nearly all computers sold come with Microsoft Windows pre-installed. In order to convince users to try free software, we must convince them to remove the operating system that came on their computers (or to divide their hard drives and make room for a new system, perceptually risking their data in the process).
With Secure Boot, new free software users must take an additional step to install free software operating systems. Because these operating systems do not have keys stored in every computer's firmware by default like Microsoft does, users will have to disable Secure Boot before booting the new system's installer. Proprietary software companies may present this requirement under the guise of "disable security on your computer," which will mislead new users into thinking free software is insecure."
I get the argument from a purist's perspective, but it's a minor problem when compared to the set of impediments "normal" users face if they decide to install a Linux distro.
If you're technical enough to be buying old computers to work around it, I bet you could figure out how to disable it when the option is right there. :)
>Can you upgrade if your computer doesn't support "Secure Boot"?
You've got it completely backwards. Windows 8 will boot on any machine, regardless of secure boot.
It is the machines that will come with secure boot enabled by default (which you can disable via the firmware setup screen) and may not be able to boot Windows 7 in the default config.
If so: 1) Buy a box with no OS 2) Install an older Windows 3) Upgrade.
Permanent path to 8 without secure boot?